CHAPTER XI 



BACTERIAL TOXINS AND ANTITOXINS 



THE ability of bacteria to produce toxin is their chief weapon 

 of offense in the production of disease. Poisonous products such 

 as acids, alkalies, hydrogen sulphid, etc., result from the growth 

 of many species, and such substances may play a minor role in 

 diseased conditions. They are, however, totally different to toxins. 

 Fortunately only a comparatively few of the vast family of micro- 

 organisms are able to produce the latter. 



Bacterial toxins are divided into two classes: (1) those inti- 

 mately connected with the bacterial protoplasm and liberated 

 only after the death of the organism, and (2) those which result 

 from living bacterial activity, are soluble, and pass out from the 

 organism into the surrounding medium. The former are spoken 

 of as endotoxins, the latter as exotoxins. 



Endotoxins. When the dead bodies of certain bacteria are in- 

 jected into animals toxic effects are frequently observed. For 

 example, if tubercle bacilli are killed by heat and injected into the 

 tissues of a susceptible animal tubercular nodules will be found 

 to have formed around the point of injection ; the dead cells of 

 typhoid bacilli and cholera spirilla likewise give rise to pathogenic 

 effects. So far it has been impossible to obtain these toxins apart 

 from the bacterial protoplasm. Since the death of bacteria must 

 be constantly occurring both in culture medium and in the body 

 during infection it is reasonable to suppose that these dead bac- 

 terial cells are disintegrated and the endotoxin thus set free. , It 

 is believed that the living members secrete a ferment that has a 

 solvent action upon the dead organisms and that upon this process 

 of autolysis the liberation of the poison depends. However this 

 may be, it is definitely known that the body cells secrete a substance 

 which has a strongly lytic action upon bacteria. 



112 



